Here are some suggestions I can think of: Mainichi no Uta, Suiga Sora, Todoroki Eiichi, Tsuine Owata, Nagine Yohji, VIICTOR (in special his Nightforce bank), Nagareboshi Yue, Kaneyama Shou (I think he even has a Korean bank, unlike most of the others)
UTAU can't sound too similar since the...